Heart attacks are a common cause of death. A heart attack occurs when a portion of the heart tissue loses circulation and becomes damaged as a result (e.g., because of blockage in the heart vasculature). Heart attacks and other abnormalities can lead to ventricular fibrillation, which is an abnormal heart rhythm (arrhythmia) that causes the heart to lose pumping capacity. If such a problem is not corrected quickly—typically within minutes—the rest of the body loses oxygen and the person dies. Therefore, prompt care of person undergoing ventricular fibrillation can be key to a positive outcome for such a person.
One common way to treat ventricular fibrillation is through the use of an electrical defibrillator that delivers a relatively high voltage shock to the heart in order to get it back into a normal pattern and a consistent, strong beat. People who have had previous problems may be implanted with an automatic defibrillator that constantly monitors the condition of their heart and applies a shock when necessary. Other such people may be provided with a wearable defibrillator in the form of a vest such as the LIFEVEST product from ZOLL Medical Corporation. Other people may be treated using an external defibrillator, such as in a hospital or via an automatic external defibrillator (AED) of the kind that is frequently seen in airports public gymnasiums and other public spaces.
People undergoing ventricular fibrillation may be more receptive to a defibrillating shock in some instances compared to others. For example, research has determined that a computation of amplitude spectrum area (AMSA) from an electrocardiogram (ECG) may indicate whether a shock that is delivered to a person will like cause defibrillation to occur or will instead likely fail. Naturally then, it is best to apply a shock when an AMSA value indicates that the shock will succeed, as opposed to when it indicates that the shock will fail.